The long range goal of this proposal is an understanding of prolactin action on the ovaries of higher mammals. To achieve this goal, we have studied the biological effects of prolactin on porcine granulosa cells in vitro. Prolactin action depends critically on maturational events which can be observed and hormonally manipulated in vitro. In the current grant period, we will extend these studies to other cell types in the porcine ovarian follicle and to cells of the porcine corpora lutea. Simultaneously, we will attempt to delineate the mechanism of prolactin effects through studies of cAMP, ornithine decarboxylase and polyamines, and prolactin, LH, and estradiol receptor levels.